Conventionally, a technology for realizing a large-sized screen with two or more display elements was applied in a large display device. In recent years, as the mobile information system has been developed to have a wireless internet function, a need of the large-sized screen is more increased. However, the large-sized screen cannot meet the most of portable characteristics of the portable display device and then a foldable type portable display device is suggested.
Generally, as flat display elements used for the portable display device, a liquid crystal display (LCD), a thin film transistor (TFT)-LCD, a field emission display (FED), a plasma display panel (PDP), an electro luminescent (EL), an electronic paper and etc., have been used.
As a portable display device with multiple display elements, a foldable type display device is suggested for increasing portable characteristics. In a prior foldable type display device, when panel housings having display elements, respectively are unfolded, there is a joint portion between the adjacent display elements. However, there are problems that the display elements of the panel housings should be precisely machined to minimize the width of the joint portion and the high reliability is need in the machining.